[外语类试卷]大学英语四级模拟试卷393及答案与解析.doc
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1、大学英语四级模拟试卷 393及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a short essay entitled On College Students Occupying Seats. You should write at least 120 words following the outline given below: 1. 在大学校园里, 占座是很普遍的现象; 2. 有人认为,大学生课前占座是不文明的行为,也有人持不同意见 3. 我的看法。 O
2、n College Students Occupying Seats 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-7, mark: Y (for YES) if the statement agrees wi
3、th the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 Change As relentlessly bad as the news about global warming seems to be, with ice at the poles melting faster th
4、an scientists had predicted and world temperatures rising higher than expected, there was at least a reservoir of hope stored here in Canadas vast forests. The countrys 1.2 million square miles of trees have been called the “lungs of the planet“ by ecologists because they account for more than 7 per
5、cent of Earths total forest lands. They could always be depended upon to suck in vast quantities of carbon dioxide, naturally cleansing the world of much of the harmful heat-trapping gas. But not anymore. In an alarming yet little-noticed series of recent studies, scientists have concluded that Cana
6、das precious forests, stressed from damage caused by global warming, insects and persistent fires, have crossed an ominous (危险的 ) line and are now pumping out more climate-changing carbon dioxide than they are sinking. Worse yet, the experts predict that Canadas forests will remain net carbon source
7、s, as opposed to carbon storage “sinks“, until at least 2022, and possibly much longer. “We are seeing a significant distortion of the natural trend,“ said Werner Kurz, senior research scientist at the Canadian Forest Service and the leading expert on carbon cycles in the nations forests. “Since 199
8、9, and especially in the past five years, the forests have shifted from being a carbon sink to a carbon source.“ Translation: Earths lungs have come down with emphysema(肺气肿 ). Canadas forests are no longer our friends. So serious is the problem that Canadas federal government effectively wrote off t
9、he nations forests in 2007 as officials submitted their plans to abide by the international Kyoto Protocol, which obligates participating governments to reduce their greenhouse gas emissions. Under the Kyoto agreement, governments are permitted to count forest lands as credits, when calculating thei
10、r national carbon emissions. But Canadian officials, aware of the scientific studies showing that their forests actually are emitting excess carbon, quietly omitted the forest lands from their Kyoto compliance calculations. “The forecast analysis prepared for the government . indicates there is a pr
11、obability that forests would constitute a net source of greenhouse gas emissions,“ a Canadian Environment Ministry spokesman told the Montreal Gazette. Canadian officials say global warming is causing the crisis in their forests. Inexorably rising temperatures are slowly drying out forest lands, lea
12、ving trees more susceptible to fires, which release huge amounts of carbon into the atmosphere. Higher temperatures also are accelerating the spread of a deadly pest known as the mountain pine beetle, which has destroyed pine forests across British Columbia and is threatening vital wood in the neigh
13、boring province of Alberta. More than 50,000 square miles of British Columbias pine forest have been stricken so far with the markers of death: needles turn bright red before falling off the tree. Bitter cold Canadian winters used to kill off much of the pine beetle population each year, naturally k
14、eeping it in check. But the milder winters of recent years have allowed the insect to grow rapidly. “Thats whats causing some of our forests to switch from a carbon sink position to a source position,“ said Jim Snetsinger, British Columbias chief forester. “Once those infested trees axe killed by th
15、e pine beetle, they are no longer taking in carbon - they are giving it off. “ Snetsiuger noted that eventually, over the course of a generation, some of the dying forests will begin to regenerate and once again begin storing more carbon than they release. But for the foreseeable future, experts say
16、, their models show that Canadas forests will stay stuck in a bad global-warming cycle, both succumbing to the effects of climate change and, as they decay and release more carbon, helping to accelerate it. That grim reality is stoking a new debate over commercial logging, one of Canadas biggest ind
17、ustries. Environmentalists contend that the extreme stresses on Canadas forests, particularly the old-growth northern forest, mean that logging ought to be sharply cut back to preserve the remaining trees-and the carbon stored within them- for as long as possible. Moreover, they argue that the proce
18、ss of logging releases even more carbon stored in the forest peat (泥炭 ), threatening to set off what they describe as a virtual “carbon bomb“ -the estimated 186 billion tons of carbon stored in Canadas forests, which is equivalent to 27 years worth of global carbon emissions from the burning of foss
19、il fuels(矿物燃料 ). “Theres only one thing which hauls all that carbon out of the forest, and thats logging,“ said Merran Smith, director of the climate program at the environmental group ForestEthics. “What we need to do is maintain as much biodiversity(生物多样性 )us we can, so we are prepared to adapt as
20、 temperatures change, so we have resilience(恢复力 ).“ But Kurz and other government scientists contend that logging less is no solution to the global warming problem and would in fact increase carbon emissions over the long term. Thats because, they argue, essential wood products for construction, fur
21、niture and other uses would have to be replaced with other man-made materials, such as plastic, steel or concrete, which require the burning of even more fossil fuels and therefore carbon emissions during their manufacturing process. “Its not as simple as saying, Log less and therefore have more car
22、bon sequestered in the forests, “ Kurz said. “That is true, but if in order to do that you have more fossil fuel emitted elsewhere, your impact on the climate may be negative. “ Instead, some scientists argue for more extensive logging of the remaining commercial forests so that older forests, which
23、 are most vulnerable to insect infestations and have nearly reached their carbon-storage capacity, can he replanted with younger trees that will take in even more carbon during their growing years. 2 Ecologists call Canadas 1.2 million square miles of trees “lungs of the planet“ for _. ( A) they bal
24、ance the world temperatures ( B) they are abundant to cleanse the earths atmosphere and play an important role in cleansing the earths atmosphere ( C) they could always suck in vast quantities of carbon dioxide ( D) they naturally cleanse much of the harmful heat-trapping gas 3 According to the scie
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- 外语类 试卷 大学 英语四 模拟 393 答案 解析 DOC
